This adds audio routing for the hvr-1300/3000/4000 cards
enabling FM audio for the I2S ADC method of the cx88.

At this time only the HVR-4000 has been tested. It
is assumed the HVR-3000/1300 are the same.
Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>